1. Field of the Invention
The present invention relates to a dielectric ceramic composition and a ceramic electronic device, and particularly relates to a dielectric ceramic composition and a ceramic electronic device showing good properties even when a dielectric layer is made thin.
2. Description of the Related Art
A multilayer ceramic capacitor as an example of ceramic electronic devices is widely used as a small-size electronic device showing high performance and being highly reliable, and many of them have been used in electrical equipment and electronic equipment. Recently, as equipment is down-sized and has higher performance, a multilayer ceramic capacitor is further demanded to downsize, improve performance, and enhance reliability.
In response to the demands, it has been promoted to make a dielectric layer of a multilayer ceramic capacitor thinner and to increase the number of layers. However, when a particle diameter of a dielectric particle is reduced in order to make the dielectric layer thinner, specific permittivity is lowered, which results in a problem of failing to obtain the desired properties.
Note that Japanese Unexamined Patent Publication No. 2008-135638 discloses a multilayer ceramic capacitor having a dielectric layer composed of a barium titanate crystal particle and a barium calcium titanate crystal particle wherein 2 kinds of rare-earth elements and other component are included with respect to the barium titanate crystal particle and barium calcium titanate crystal particle. It also discloses that the multilayer ceramic capacitor has high insulation resistance, and shows small reduction of insulation resistance over time in highly accelerated life test.
However, the thickness of the dielectric layer of the multilayer ceramic capacitor disclosed in Examples of Japanese Unexamined Patent Publication No. 2008-135638 is 2 and it has been found that the above problem cannot be solved when the dielectric layer is further made thinner.